Hearing loss affects 55 million individuals in the United States. Listeners with severe hearing loss experience unique speech perception problems that are associated with poor spectral resolution, along with reduced audibility, and reduced dynamic range. Little is known about the relative contribution of each for people with severe hearing loss. Several studies have reported varied rehabilitation success rate among listeners with severe hearing loss. Previous work has identified a subset of listeners with severe loss for whom improving audibility did not improve consonant recognition scores, in the same manner as their cohort with equivalent thresholds. Quantifying the relationship between spectral resolution and speech recognition could help 1) guide clinical decisions on setting compression parameters for their hearing instruments. 2). It could explain the often reported variance in scores for nonlinear amplification among listeners with apparently equal severe thresholds. The specific aims of the proposed project are to 1) to evaluate different methods of assessing spectral resolution. 2) To evaluate the relationship between spectral resolution and consonant recognition. 3) To evaluate the relationship between spectral resolution and performance for amplitude compressed speech. Adult listeners with severe sensorineural hearing loss will participate in this study. Each subject will undergo standard audiologic and cognitive testing to determine candidacy for the study. Spectral resolution and consonant recognition will be measured using two different methods and test stimuli. The diagnostic value of spectral resolution will be evaluated for 1) explaining performance variance across listeners with similar thresholds. 2) determining individual listener's susceptibility to distortion resulting from amplitude compression. The information gained from this study can be used in future development of hearing aid amplification and signal processing strategies for listeners with severe hearing loss. Listeners who are unable to detect spectral cues might benefit from more sophisticated signal processing, such as spectral enhancement. This information will also be useful for customizing rehabilitative programs for listeners with severe hearing loss.